Art of detinning tin-scrap and the like material.



o'r'ro K. .ZWINGENBERGER,

OF TOMPKINSVILLE,

NEW YORK.

ART OF DETINNING TIN-SCRAP AND THE LIKE MATERIAL.

Specification of Letters Patent.

Patented Mar. 19, 1918.

No Drawing. Application filed June 8, 1911, Serial No. 631,908. Renewed August 15,1917. Serial No.

To all whom it may concern:

Be it known that I, OTTO K. ZWINGEN- BERGER, a subject of the King of Saxony, residing at 8 Wiener Place, Tompkinsville, S. 1., in the county of Richmond and State of New York, have made certain Invention in the Art of Detinning Tin-Scrap and the like Material, of which the following is a specification.

My invention relates to the art of detinning tin scrap and the like material by means of chlorin gas whereby the tin is taken ofi the sheet iron and the tin is transformed into tin-tetrachlorid. The object of my invention is to exclude the harmful influence of water which may come into con- 1 tact with the raw material to be detinned,

owing to the moisture in the chlorin gas or in the moisture in the atmosphere or whatever sources there may be.

In the detinning of tin scrap by means of chlorin gas the influence of water, which may be in the chlorin gas or may adhere in hardly noticeable traces to the tin scrap, is a source of great losses and troubles. If there is any water vapor in the detinning vessels the yield of tin-tetrachlorid is reduced in the degree water is present, for tintetrachlorid forms crystalline compounds with this water and these crystals cover then the inside walls of the detinning vessel as well as the tin scrap itself so that the whole mass looks just as'if it were covered with fine snow. It is obvious that tin-tetrachlorid cannot be easily removed out of the reaction vessels when it has entered this crystalline form especially in view of the annoying properties of both the chlorin gas and liquid tin-tetrachlorid held by the fine crystals just like by a sponge, whereby great losses are sustained.

Further losses may occur for the fact that tin plate,'covered with such fine crystals, is no more so easily accessible to chlorin gas so that the tin is but incompletely taken off the sheet iron, the resulting iron scrap being of less value.

Further losses may'occur, as water, which accidentally is carried into the detinning vessels, is the cause for the formation of iron chlorid whereby great heat is generated which invites still greater formation of iron chlorid leading to great losses of chlorin gas. For all these losses the harmful influence of water in the detinning by means of chlorin gas has always been given much attention to reduce these losses as much as possible.

Many suggestions have been made in regard to this point. Suggestions to that point were mostly based on mechanical manipulations, for example to reduce the content of water in chlorin to the lowest possible minimum by liquefying the chlorin and then gasifying it again. Other suggestions are based on the absorption of water out of the chlorin gas by certain chemicals. Most of these suggestions are working with some success in other branches of the chemical industry, but for the detinning industry these methods are not reliable enough, for here even small traces of water, which would not be of any concern in the manufacture of many chemicals, are a great handicap in this art, causing much trouble and heavy losses.

All chemicals which absorb water, arrive after a certain period at the limit when they will be no more reliable in their action with regard to this point and it is especially at such critical moments when water in small quantities is easily carried into the detinning vessels. The tin scrap may be dried in heating chambers to be deprived of its adhering water, but it has been found out that, even All-the methods to remove the water out process.

Said reaction may be broughtabout by mixing with the chlorin gas another gaseous substance, such as sulfur-dioxid gas for instance, which, owing to the presence of the undesirable water will enter a reaction with the chlorin gas by which all the water is consumed and is thus removed, as there is seen from the following equation:

these three bodies being transformed into sulfuric acid and hydrochloric acid.

be called thesecon'daryprocess, which has no disturbing influence on the detlnning process itself nor on the commercial prod' ucts generated in this process.

For carrying out the detinning by means of chlorin gas'with an adniixture of sulfurdioxid gas one has for the first. to find out by careful analytical tests and other conthat at the end or at a short time before the end of the detinning operation the required quantity of sulfur-dioXid gas has been chargedinto the vessel with the chlorin gas needed for the detinning, suitably a small excess of sulfur-dioxid being applied to carry out this 'abovem'entioned secondary reaction to consume the water.

I may say here that it is of advantage to apply a small excess 'of sulfur-dioxid gas over the amount one has established by the analytical "test and that in 'theav erage 'an excess of about five per cent. sulfur-dioxid gas has'been found tobe beneficial to the By this'surplus of sulfur-dioxid gas especially good conditions seem to prevail'resulting' in an absolute removal of the water and increasing at the same time the yield of'li'quid tin-tetrachlorid as this heavy liquid has no more chance to take on the crystalline form and therefore cannot be held anymore by a sponge like obstruction but can easily be run off-into the receptacles attached to' the bottom of" the vessels by means of a drainage pipe. I

It is obvious that this method is notto be interpreted as an inducement to be less care ful in the drying operations for both chlorin gas and tin scrap, as 'it' is 'of 'course a necessity-to make the b'e st use of the expensive chlorin gas for the detinning process proper, but the invention offersfsafety against the great rise in "temperature during the detinning process owing to the presence of water 'as well as againstthe losses of chlorin tin by the complicationsresulting from iron burning, up to ironchlorid for reasons given above; Both the chlorin and the'sul This reaction, going on simultaneously 7 with the detnmmg process, may therefore chlorin gas one does we'll-to payattention' to another point and to regulate the quantities of added sulfur-dioxid gas accordingly.

This point lies in the factthat a considerable part of the water sits on the tin scrap and that it is therefore advisable to increase the sulfur-diox d gas during the first few hoursand to decrease it then to maintain it evenly in the'furthercourse'of the operation.

The operation is carried out by simply conducting the two gases over the loosely bundled scrap, without applying any special pressure or'underpres'sure."

The invention is not restricted to the use of sulfur-dioXid for the secondary reaction, nor is 1t to be consldered to be an inert gas which might simply act as a mere diluent of the chlorin gas as occasionally applied 1n detinmng scrap with dry chlorin gas in order to moderate'the reaction, but

itstands in the specification as a mainirepresentative of a class of gases or gaseous substances which in the presenoe of chlorin and: water undergo a chemical process whereby the water is consumed; one of the resulting products of said process being nydr'ochloric acid whereas the other product or products willnot embodyfchl'orin. The

advantages of the detinning process with chl'orin and sulfur-dioxid gas-or any other similarly'working gas, consist in an: easy control of the process as now the operation is going on'more evenly because the temperature in the-detinning vessel is better under control and many accidents are avoided, in a: greater and more'uniform yield of liquid tin'tetrachlorichin an ea'sier and more completeremoval of thesurplus of chlorin gas, with the traces of'sulfur dioXid gas, and the remaining tin tetra chlorid at the end lofthe reaction simply. blowing out the vessel with compressed air, in the greater economy by avoiding unnecessary losses and in the freedom from all hape hazards leading to losses and annoyances, especially when the gas is admitted at the top of the vessel and leaves at the bottom to enter another vessel at the top and soionr The main source of trouble, viz; the waters being automatically removed in a chemical cal reaction.

2. The process of detinning tin scrap and the like material, consisting in treating tin scrap with chlorin gas in the presence of moisture and eliminating the influence of said moisture by decomposing it by chemical reaction between another gas, chlorin and Water.

3. The process of detinning tin scrap and the like material, consisting in treating tin scrap With chlorin gas in the presence of moisture and consumin said moisture by a chemical reaction furnishing hydrochlorid acid and another product not embodying chlorin.

a. The process of detinning tin scrap and the like material consisting in treating tin sc'ap in the presence of moisture With a mixture of chlorin gas, admitting an excessive quantity of another gaseous substance and decomposing the moisture by its action with the chlorin and the other gaseous substance.

5. The process of detinning tin scrap or the like material, which consists in treating tin scrap with a mixture of both chlorin and sulfur dioxicl gas.

6. The process of detinning tin scrap and the like material, consisting in treating tin scrap in the presence of moisture With a mixture chlorin and sulfurdioxid gas.

The process of detinning tin scrap and the like material, consisting in treating tin scrap in the presence of moisture With a mixture of chlorin and of sulfur dioxid gas, the latter being in excess of the quantity necessary for consuming the Water by 45 a chemical reaction between the Water and the constituents of the gas mixture.

8. The process of detinning tin scrap and the like material, consisting in treating tin scrap in the presence of moisture with a mixture of clilorin and sulfur dioxid gas, thoroughly mixed before being admitted the reaction material, and consuming the Water by a chemical reaction between the Water and the constituents of the gas miX- ture.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

OTTO K. ZWINGENBERGER.

Witnesses RAE LIVINGSTON EGBERT, WALTER E. HEAR Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. G. 

